Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability

Added to KEV
2021-11-03
Federal due date
2021-11-17
Vendor
Microsoft
Product
Windows
EPSS
98.8th percentile (score 0.721, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2021-33742

CISA short description

Microsoft Windows MSHTML Platform contains an unspecified vulnerability that allows for remote code execution.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.